<template>
  <!-- 商品分类导航 -->
  <div class="type-nav">
    <div class="container">
      <div @mouseleave="leaveIdenx" @mouseenter="enterShow">
        <h2 class="all">全部商品分类</h2>
        <!-- 过度动画 -->
        <transition name="sort">
          <!-- 三级联动 -->
          <div class="sort" v-show="show">
          <!-- 编程式导航+事件委派实现路由的跳转与传参 -->
          <div class="all-sort-list2" @click="goSearch">
            <div
              class="item"
              v-for="(c1, index) in categoryList"
              :key="c1.categoryId"
              :class="{ cur: currentIndex == index }"
            >
              <h3 @mouseenter="changeIndex(index)">
          <a :data-categoryName="c1.categoryName" :data-category1Id="c1.categoryId">{{ c1.categoryName }}</a>
              
              </h3>
              <!-- 二级，三级分类 -->
              <div
                class="item-list clearfix"
                :style="{ display: currentIndex == index ? 'block' : 'none' }"
              >
                <div
                  class="subitem"
                  v-for="(c2, index) in c1.categoryChild"
                  :key="c2.categoryId"
                >
                  <dl class="fore">
                    <dt>
                   <a :data-categoryName="c2.categoryName" :data-category2Id="c2.categoryId">{{ c2.categoryName }}</a>
                    </dt>
                    <dd>
                      <em
                        v-for="(c3, index) in c2.categoryChild"
                        :key="c3.categoryId"
                      >
                     <a :data-categoryName="c3.categoryName" :data-category3Id="c3.categoryId">{{ c3.categoryName }}</a>
                      </em>
                    </dd>
                  </dl>
                </div>
              </div>
            </div>
          </div>
        </div>
        </transition>

     
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">尚品汇超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
import { mapState } from "vuex";
// 引入方式:是把lodash全部功能函数引入,要加_.
// import _ from 'lodash'; 
// 最好的引入是按需引入
import throttle  from "lodash/throttle";


export default {
  name: "TypeNav",
  data() {
    return {
      // 存储鼠标在哪个一级分类
      currentIndex: -1,
      show:true
    };
  },
  methods: {
    // 鼠标进入修改响应式数据currentIndex属性
    // changeIndex(index) {
    //   this.currentIndex = index;
    //   // index一级分类索引值
    // },
    // 节流
    changeIndex:throttle(function(index){
      this.currentIndex = index;
    },50),
    enterShow(){
  // 当鼠标进入全部商品分类让三级联动显示
        this.show = true;
    },

    // 鼠标移除
    leaveIdenx() {
      this.currentIndex = -1;
     // 当鼠标离开全部商品分类让三级联动隐藏
      if(this.$route.path!='/home'){
      this.show = false;
    }
    },
    // 三级联动进行路由跳转
    goSearch(event){
        // 三级联动如果用route-link跳转会导致卡顿
        // 用编程式导航会导致循环过多
      // 最好解决方案：编程式导航+事件委派
      // /第一个问题:div父节点子元素太多【h3、h2、em、dt、dd、dl...a】？你怎么知道你点击的一定是a
      // 解决办法给a标签添加自定义属性
      //第二个问题:要区分一级分类、二级分类、三级分类的a标签【category1Id|category2Id|category2Id】
      // dataset属性可以获取节点的自定义属性与属性值
     let element = event.target;
     let { categoryname, category1id, category2id, category3id } = element.dataset
     if(categoryname){
      //  整理路由跳转的参数
        let location = {name:'search'};
        let query = {categoryName:categoryname};
        // 一级分类、二级分类、三级分类的a标签
       if(category1id){
           query.category1Id =category1id;
       }else if(category2id){
         query.category2Id =category2id;

       }else{
        query.category3Id =category3id;
       }
      //  整理参数
      // console.log(location,query);
      // 判断：如果路由跳转的时候，带有params参数，也要传递过去，进行合并参数
      if(this.$route.params){
      location.params = this.$route.params;
      location.query = query;
      // 路由跳转
      this.$router.push(location);
      
      }
      
      

     }
    }
  },
  
  mounted() {
  
    // 组件挂载完毕，让show属性变为false
    // 如果不是home路由组件，将typeNav进行隐藏
    if(this.$route.path!='/home'){
      this.show = false;
    }
  },
  // 获取服务器的数据
  computed: {
    ...mapState({
      // categoryList:(state)=>{
      //   return state.home.categoryList;
      // }
      categoryList: (state) => state.home.categoryList,
    }),
  },
};
</script>

<style lang="less">
.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 30px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                  }
                }
              }
            }
          }

          // &:hover {
          //     .item-list {
          //         display: block;
          //     }
          // }
        }
        .cur {
          background-color: skyblue;
        }
      }
    }
    // 过度动画
    .sort-enter{
      height: 0px;
    }
    .sort-enter-to{
        height: 461px;
    }
    .sort-enter-active{
      transition: all .5s linear;

    }
    // 定义动画时间，速度


  }
}
</style>
